const trim = function (str, type) { // 去除空格， type:  1-所有空格  2-前后空格  3-前空格 4-后空格
    type = type || 1
    switch (type) {
        case 1:
            return str.replace(/\s+/g, '')
        case 2:
            return str.replace(/(^\s*)|(\s*$)/g, '')
        case 3:
            return str.replace(/(^\s*)/g, '')
        case 4:
            return str.replace(/(\s*$)/g, '')
        default:
            return str
    }
}